West Pacific/2015/09W/Archive/5
Public advisory TROPICAL STORM CHAN-HOM PUBLIC ADVISORY NUMBER 5 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST WED JUL 01 2015 ...CHAN-HOM REMAINS DISORGANIZED ON ITS WEST-NORTHWEST TREK... SUMMARY OF 12:00 PM JST...03:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...10.9N 159.0E CENTER POSITION CONFIDENCE: AVERAGE ABOUT 280 MI...450 KM NNE OF PALIKIR, MICRONESIA ABOUT 975 MI...1,570 KM ESE OF HAGÅTÑA, GUAM MAXIMUM SUSTAINED WINDS...40 KT...45 MPH...75 KM/H MINIMUM BAROMETRIC PRESSURE...1001 MB...29.56 INCHES PRESENT MOVEMENT...WNW AT 14 KT...16 MPH...26 KM/H DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 12:00 pm JST, the center of Tropical Storm Chan-hom was situated near 10.9N, 159.0E, about 280 miles (450 km) north-northeast of Palikir, Micronesia, or about 975 miles (1,570 km) east-southeast of Hagåtña, Guam. Maximum sustained winds were 40 knots (45 mph, 75 km/h), with higher gusts. The minimum barometric pressure was 1001 millibars (hPa; 29.56 inHg), and the cyclone was moving swiftly west-northwestward at 14 knots (16 mph, 26 km/h). Environmental conditions are expected to favor steady to quick strengthening throughout the forecast period. On the current forecast track, Chan-hom poses a threat to the southern and central Mariana Islands, and residents there should closely monitor the progress of this cyclone. NEXT ADVISORY ------------------- Next complete advisory at 6:00 pm JST. $$ Forecaster TAWX14 Discussion TROPICAL STORM CHAN-HOM DISCUSSION NUMBER 5 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST WED JUL 01 2015 Chan-hom continues to be a disheveled cyclone this evening. Although satellite animations show an impressive convective mass in association with a vigorous mid-level circulation, the actual surface low remains clearly exposed and very elongated. Satellite intensity estimates were an unchanged T2.5/35kt from both SAB and JTWC, with the recent value from UW-CIMSS ADT at T2.2/32kt. However, given the persistence and intensity of the convective mass in the absence of any microwave passes, the initial intensity is being held at 40kt. The current structure of Chan-hom makes it clear that the upper-level setup is not currently conducive for the tropical storm. In fact, maps from UW-CIMSS indicate that shear is higher than seen earlier, in the range of 20 to 30 knots. However, water vapor animations indicate that upper-level outflow is beginning to expand in all quadrants except the east, a sign that anticyclonic flow aloft is beginning to become established. This, in addition to rising sea surface temperatures and ocean heat content, should favor steady intensification over the coming days. Once an inner core is established, the potential exists for rapid intensification as shown by several reliable models. One factor that will continue to be monitored is Chan-hom's interaction with nearby Invest 94W; these interactions are not yet well documented and well understood in the meteorological community. All told, the updated intensity forecast indicates Chan-hom to reach typhoon intensity by 48 hours and major hurricane equivalency by the end of the forecast period. After slowing to a halt earlier this afternoon, Chan-hom has quickly accelerated toward the west-northwest. The cyclone is currently being steered under the influence of a 594dm mid-level ridge across the northern West Pacific, and this steering mechanism is expected to remain in place for the next 24 to 36 hours. Thereafter, global models are in good agreement that interaction with nearby Invest 94W will cause Chan-hom to pivot southwestward. By 72 hours and beyond, an upper-level trough digging into Japan and surrounding regions is expected to erode the western periphery of the aforementioned ridge, acting to turn Chan-hom on a northwestward course. This afternoon's model runs were further south compared to this morning's runs, and the updated WHFC track has too shifted southward to account for this change. Chan-hom appears to be a substantial threat to the central and southern Mariana Islands, and residents there should monitor the progress of the cyclone closely. INIT 01/0300Z 10.9N 159.0E 40 KT 45 MPH 12H 01/1200Z 11.4N 157.6E 45 KT 50 MPH 24H 02/0000Z 11.7N 154.2E 50 KT 60 MPH 36H 02/1200Z 11.5N 151.7E 55 KT 65 MPH 48H 03/0000Z 11.3N 149.1E 65 KT 75 MPH 72H 04/0000Z 13.1N 146.2E 75 KT 85 MPH 96H 05/0000Z 14.8N 143.9E 85 KT 100 MPH 120H 06/0000Z 17.9N 140.7E 105 KT 120 MPH $$ Forecaster TAWX14